The invention relates to an energy management system for a transport device, to a method for operating a transport device and to a transport device. Transport devices for transporting goods and/or people are known, for example, as heavy goods vehicles, passenger vehicles, transporting vehicles and/or lifting devices for, for example, ISO containers or the like (for example lifting device at docks or at a container depot) or else as driverless transport vehicles, in particular for container ports.
Transport devices are in particular fuel-electric vehicles and/or fuel-electric lifting devices in which an internal combustion engine is used as the energy source for obtaining electrical current by means of a generator. The internal combustion engine is provided for combusting fuel which can be carried along by the transport device in a fuel tank. Fuels are, for example, gasoline, diesel, natural gas, hydrogen, etc. The internal combustion engine is advantageously a diesel engine which is mechanically coupled to an electrical generator for the purpose of generating electrical current. The electrical energy generated by means of the electrical generator can be used for an electrical energy consumer. The electrical energy consumer is in particular an electrical drive. The electrical drive is used, for example, for the continued motion of the transport device and/or for lifting and/or lowering loads of a lifting device, the lifting device also being, for example, a transport device.
If the transport device is, for example, a fuel-electric vehicle, such as a straddle carrier (SC) or a rubber-tired gantry crane (RTG) or an automated guided vehicle (AGV), these systems are used in particular for the transfer of goods. In this case, they are used in particular for lifting and lowering as well as transporting loads. Loads are, for example, goods, containers, people, etc. Energy is required for lifting the load, and energy is released for lowering the load. The greater the load, the greater the energy.
In this case, a fuel which is combusted in an internal combustion engine such as, for example, a diesel engine, is often used as the primary energy source. A generator which is coupled to the diesel engine or to another machine, such as, for example, a synchronous generator or else a fuel cell, with which no generator is required, are used for feeding an electrical circuit. The electrical circuit is in the form of an intermediate circuit, for example. For example, electric motors for running gear and/or lifting gear of the transport device are coupled to the electrical circuit. The coupling advantageously takes place by means of a power converter. A battery, a flywheel and/or a capacitor unit (having ultra capacitors, for example) are used as the energy store of the transport device, for example.
A store provided for the consumption of energy in the transport device, such as, for example, an electrical energy store, a chemical energy store and/or a fuel reservoir/tank, is delimited in terms of its storage volume. If the energy store is empty, it needs to be refilled. In order to ensure that the transport device is ready for use, it is known that, when the stored energy falls below a specific minimum store value, a demand for refilling the store(s) takes place. If, for example, the energy store for the fuel is below a specific threshold, this is indicated and a refilling operation is demanded. One disadvantage here is the fact that this refilling operation needs to take place, for example, at a point in time at which a transport task or measure of the transport device needs to be interrupted.
In order to be able to fulfill as many transport tasks or equivalent transport measures as possible, efficient energy management is necessary. DE 200 01 113 U1 has disclosed, for example, a drive apparatus for a fuel-electrically driven vehicle. In fuel-electrically driven vehicles, the vehicle electrical supply system is usually produced/fed via a synchronous generator. In order to save energy, a system can be provided which makes it possible to operate at energy-saving working points. This means that, for example, the diesel engine is preferably operated at an operating point at which as little diesel as possible is consumed. By means of the speed of the diesel assembly being regulated, it is therefore possible to achieve optimization of operation. Excess energy can be stored in an energy buffer store (for example a battery, a flywheel, a capacitor) and can be called upon there for energy consumers. One disadvantage here is the fact that the diesel engine or the generator as the energy source always needs to be designed in terms of their power such that they cover the maximum possible required power. This is disadvantageous, for example, for rubber-tired transshipment devices which are primarily operated with a changing load. These devices are always designed for the maximum load to be expected and therefore are provided with considerably excess dimensions. This also applies to the diesel-electric assembly.
DE 198 26 551 already also discloses, for example, a control system which can be used universally for a hybrid system comprising at least one energy store and an energy source. In this case too, there is the problem of the necessary overdimensioning of the assembly.